The present invention relates to a method and a device for controlling a motor, in particular a drive motor for opening and closing a door, in which the motor is controlled using a pulse-width-modulated switching signal which is divided into a predefinable number of pulse-width-modulated control signals for driving a bridge circuit for a number of functional channels.
A variety of designs of devices for controlling the operation of an automatic door are known.
In this case, pulse-width-modulated control methods and devices, in particular, are used to control, in particular, the speed and/or direction of rotation of the motors, particularly of brushless DC motors and DC motors controlled using rotor rotary position sensors, for example Hall sensors, the motor current being manipulated on the basis of a control signal in order to change the speed.
It is known practice to drive a brushless DC motor using a bridge circuit, in particular a semiconductor bridge circuit, the motor being arranged in the bridge branch of the bridge circuit formed from electronic switching elements (usually transistors). The switching elements are driven by a driver or amplifier stage on the basis of sensor signals, for example from a contactless rotor rotary position sensor, generally a Hall element (Hall IC). In addition, drive principles without sensors are also possible.
In this case, a pulse-width-modulation controller is used to manipulate the current for the purpose of setting the speed, commutation-dependent current pulses each being chopped up into clock pulses at a constant clock frequency. In this case, the pulse width of the clock pulses is variable. This means that it is possible to indirectly change the effective motor current and thus the speed by changing the duty ratio.
Such pulse-width-modulated controllers of motors are known, for example, from DE 19543873 A1.
In the event of a fault, for example in the event of a short circuit, overload, overspeed or overexcitation, the motor is switched off using a separate independent protective circuit.
DE 100 59 173 C1 and US 2006/0056212 A1 also disclose drive control processes for a three-phase AC motor via an inverter, which drive control processes make it possible to “safely stop” and “brake” the motor “by armature short-circuiting”.